Loading andin vitro Controlled Release of Indomethacin Using Amphiphilic Cholesteryl-Bearing Carboxymethylcellulose Derivatives

Interfacial Selective Study on the Gelation Behavior of Aqueous Methylcellulose Solution via a Quartz Crystal Microbalance

It is important to understand the interfacial structure and physical properties of a polymer material to improve its function. In this study, we used a quartz crystal microbalance (QCM) and neutron reflectivity (NR) measurements to evaluate the viscoelasticity and structure of an aqueous methylcellulose solution near the gold interface. The apparent shear modulus, which was calculated from the complex frequency, was used to assess gelation behavior. The apparent shear modulus determined via the QCM suggested high-frequency rheological properties that reflected the relaxation of skeletal stretching and rotational motion of polymer segments, as well as cooperative motion of the various functional groups. The gelation temperature was found to be lowered at the interface in comparison with that of the bulk. It is suggested that the QCM can evaluate the shear modulus accompanying the gelation near the interface. The interfacial segregation on the gold substrate caused by the surface free energy and long-range van der Waals interaction was observed from NR measurements.

Recent Developments of Carboxymethyl Cellulose

Carboxymethyl cellulose (CMC) is one of the most promising cellulose derivatives. Due to its characteristic surface properties, mechanical strength, tunable hydrophilicity, viscous properties, availability and abundance of raw materials, low-cost synthesis process, and likewise many contrasting aspects, it is now widely used in various advanced application fields, for example, food, paper, textile, and pharmaceutical industries, biomedical engineering, wastewater treatment, energy production, and storage energy production, and storage and so on. Many research articles have been reported on CMC, depending on their sources and application fields. Thus, a comprehensive and well-organized review is in great demand that can provide an up-to-date and in-depth review on CMC. Herein, this review aims to provide compact information of the synthesis to the advanced applications of this material in various fields. Finally, this article covers the insights of future CMC research that could guide researchers working in this prominent field.

Dissolution of amorphous nifedipine from micelle-forming carboxymethylcellulose derivatives

We show that a novel amphiphilic graft copolymer combining the biodegradability and biocompatibility of oxidized carboxymethylcellulose (CMC) with that of hydrophilic poly(ethylene glycol) (PEG), and hydrophobic dodecylamine (DDA), improves the solubility and dissolution performance of nifedipine (NIF), considered as a model hydrophobic drug. The hydrophobic components of the graft copolymer have the multiple effect of favouring micelle formation and loading. At the same time, the interaction between the hydrophobic core and NIF has the secondary effect to suppress drug crystallization, favouring its dissolution, and to increase photostability. Oxidized CMC-g-PEG-DDA micelles reached values of drug concentration, loading capacity and encapsulation efficiency as high as 340 μg mL^-1, 6.4 % and 34.1 %, respectively. Loaded micelles showed a good stability with a limited release profile at pH 1.2, whereas at pH 7.4 the swollen cores enable much higher and progressive release, that reaches 3.4 and 6.6 % after 3 and 5 h, respectively, corresponding to very competitive concentration of 34 and 66 μg mL^-1.

Multifunctional hybrid nanoparticles based on sodium carboxymethylcellulose-graft-histidine and TPGS for enhanced effect of docetaxel

Multifunctional hybrid nanoparticles that comprised of sodium carboxymethylcellulose-graft-histidine (CMH) and TPGS were designed for overcoming MDR of docetaxel.

Nanostructured lipid carriers modified with PEGylated carboxymethylcellulose polymers for effective delivery of docetaxel

An amphiphilic carboxymethylcellulose-graft-histidine/methoxypolyethylene glycol (CMP) copolymer was firstly synthesized to modify nanostructured lipid carriers (NLCs) for effective delivery of docetaxel.

Downregulation of VEGF mRNA expression by triamcinolone acetonide acetate-loaded chitosan derivative nanoparticles in human retinal pigment epithelial cells

BACKGROUND

The purpose of this study was to investigate the downregulation of mRNA expression of vascular endothelial growth factor (VEGF) by triamcinolone acetonide acetate (TAA)-loaded chitosan nanoparticles in human retinal pigment epithelial cells.

METHODS

TAA-loaded deoxycholic acid-modified chitosan (TAA/DA-Chit) nanoparticles were prepared via a self-assembly mechanism, and their morphology and zeta potential were examined by transmission electron microscopy and zeta potential analysis, respectively. DA-Chit and TAA/DA-Chit nanoparticle toxicity was evaluated using a Cell Counting Kit-8 assay. The efficiency of cellular uptake was determined using fluorescein isothiocyanate-labeled DA-Chit nanoparticles, in place of TAA/DA-Chit nanoparticles, assessed by both inverted fluorescence microscopy and flow cytometry. Downregulation of VEGF mRNA expression by TAA/DA-Chit nanoparticles was further investigated by real-time reverse transcription polymerase chain reaction (RT-PCR) assay of the treated human retinal pigment epithelial cells.

RESULTS

TAA/DA-Chit nanoparticles were prepared with a TAA-loading capacity in the range of 12%-82%, which increased the water solubility of TAA from 0.3 mg/mL to 2.1 mg/mL. These nanoparticles showed oblate shapes 100-550 nm in size in transmission electron microscopic images and had positive zeta potentials. The Cell Counting Kit-8 assay indicated that the DA-Chit and TAA/DA-Chit nanoparticles had no toxicity and low toxicity, respectively, to human retinal pigment epithelial cells. Fluorescein isothiocyanate-labeled DA-Chit nanoparticle uptake by human retinal pigment epithelial cells was confirmed by inverted fluorescence microscopy and flow cytometry. Real-time RT-PCR assay showed that the VEGF mRNA level decreased after incubation of human retinal pigment epithelial cells with TAA/DA-Chit nanoparticles.

CONCLUSION

TAA/DA-Chit nanoparticles had a downregulating effect on VEGF mRNA expression in human retinal pigment epithelial cells and low cytotoxicity, which might be beneficial characteristics for the development of future treatment for diabetic retinopathy.

Interplay between gelation and phase separation in aqueous solutions of methylcellulose and hydroxypropylmethylcellulose

Thermally induced gelation in aqueous solutions of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) has been studied by rheological, optical microscopy, and turbidimetry measurements. The structural and mechanical properties of these hydrogels are dominated by the interplay between phase separation and gelation. In MC solutions, phase separation takes place almost simultaneously with gelation. An increase in the storage modulus is coupled to the appearance of a bicontinuous structure upon heating. However, a thermal gap exists between phase separation and gelation in the case of HPMC solutions. The storage modulus shows a dramatic decrease during phase separation and then rises in the subsequent gelation. A macroporous structure forms in the gels via "viscoelastic phase separation" linked to "double phase separation".

Evaluation of amylose used as a drug delivery carrier

The enzyme-dependent conjugates of indomethacin and amylose (Am-IND) were synthesized at room temperature using N,N'-dicyclohexylcarbodiimide (DCC) as a coupling agent and 4-(N,N'-dimethylamino) pyridine (DMAP) as a catalyst. Their structures were characterized by FTIR and (1)H NMR analyses, and the results indicated that the IND residues were conjugated with amylose backbones through ester bonds. For the conjugate with a lower IND content, the better water absorption property was advantageous for enzymes diffusing into the swollen conjugate, resulting in biodegradation of the conjugates and release of IND. In vitro biodegradation evaluation indicated that the Am-IND conjugates were biodegraded in the simulated media of the intestines. In vitro drug release experiments showed that the Am-IND conjugates exhibited a sustained release behavior in the simulated media of the intestines, while IND was hardly released in the simulated gastric fluid. These features provide a great opportunity to use the conjugates as a prodrug for intestinally targeted and controlled release of IND through oral administration. This study may lead to the development of effective methods for utilizing amylose as a new drug delivery carrier.

In situ crosslinkable hydrogel formed from a polysaccharide-based hydrogelator

In situ crosslinkable hydrogel formed from an amphiphilic amylopectin-based hydrogelator in aqueous solution was investigated with respect to its viscoelasticity, structure as well as protein encapsulation and release. Different from the physical hydrogel formed from an aqueous amylopectin system of sufficiently high concentration, such a hydrogel could be formed rapidly at room temperature and exhibit enhanced viscoelastic properties, mechanical strength, and shear thinning behavior. In addition, it has a more complex network structure with a higher fractal dimension due to intermolecular hydrophobic interactions and macromolecular chain entanglements. By circular dichroism analyses and in vitro release experiments, this hydrogel material was found to have a great potential as new matrix for the entrapment and sustained release of bovine serum albumin.

Synthesis and anaerobic biodegradation of indomethacin-conjugated cellulose ethers used for colon-specific drug delivery

Water soluble cellulose ethers, including methylcellulose and two hydroxyethylcelluloses with different molecular weights, were conjugate with indomethacin at room temperature. The chemical structures of the conjugates were characterized by FTIR, (1)H NMR and UV-vis spectroscopy. The results confirmed that different amounts of IND residues were covalently bonded to cellulose ether backbones through ester linkages. Their anaerobic biodegradation in colonic fermentation was investigated by gel permeation chromatography, gas chromatography and UV-vis spectroscopy. These conjugates were found to have different biodegradabilities, depending on the cellulose ether used and the amount of conjugated indomethacin residues. In vitro release experiments showed that hydroxyethylcellulose-based conjugates with low IND residues content could exhibit a sustained drug release behavior in colonic fermentation and were stable in the simulated media of the stomach and small intestine. Therefore, they are promising candidates for future applications in colon-specific drug delivery.